Gareth Patterson, Associated Press
Democratic presidential candidate Hillary Rodham Clinton speaks at a grassroots organizing meeting at Philander Smith College Monday, Sept. 21, 2015, in Little Rock, Ark.

DES MOINES, Iowa — Hillary Rodham Clinton is breaking her longstanding silence over the construction of the Keystone XL pipeline, saying at a campaign stop in Iowa that she opposes the controversial project.

Clinton says the project has been a distraction and she doesn't believe it's in the best interests of "what we need to do to combat climate change."

The former secretary of state had previously said she shouldn't take a position on the issue, saying she didn't want to interfere with the Obama administration's deliberations.

But she has expressed her impatience in recent weeks over the pipeline decision, which is vigorously opposed by environmental activists.

Clinton announced her decision moments after Pope Francis arrived in Washington at the start of a closely watched visit to the United States.